Previously proposed is a walking assistance device that includes a power generator such as an electric motor to apply a walking assistance force to a lower limb of a user for the purposes of assisting the walking movement of the user, and/or rehabilitating the walking impairment of the user. See Japanese laid open patent publications JP2006-320351A and JP2008-134086A (patent documents 1 and 2), for instance.
Such a walking assistance device typically includes a pelvic frame consisting of a C-shaped main frame configured to be worn on a pelvic part of the user and extending from a lower hack part of the user to either side of the pelvic part of the user, and an abdominal belt for securing the main frame to the pelvic part of the user. Each free end of the main frame is fitted with a power generator that applies a walking assistance force to the lower limb of the user.
The pelvic frame is designed to secure the power generator for producing the walking assistance force to the pelvic part of the user, and is required to be able to support the reaction of the force (torque) produced by the power generator (in particular, the reactive torque around a pivot center of the hip joint) and favorably fit on the user without causing any discomfort.
However, the conventional arrangement was not totally satisfactory in this regard. More specifically, as the pelvic frame had a limited capacity in preventing the rotation of the pelvic frame around the pivot center of the hip joint when the pelvic frame is worn by the user, the reaction of the walking assistance force produced by the power generator is not adequately supported, and this caused the twisting of a part of the pelvic frame.
The pelvic frame is desired to be worn and removed with as little effort as possible, but the previously proposed pelvic frames were not totally satisfactory in this regard. In particular, the user of the pelvic frame may be handicapped in some cases, and there is an acute need for simplifying the wearing and removing of the pelvic frame.